Farhan ArshadThe best asset in the Side Hustle Summit funnel was the free one. Before selling anything, the organisers gave away an income calculator: a few questions about your situation, and back came a personalised monthly figure. It segmented two million registrants, it felt like a tool rather than a download, and it put a number in each person’s head that they had produced themselves. Most businesses are still handing out a PDF that gets saved to a downloads folder and never opened.
I rebuilt that idea for a different kind of business, a local service company, and the working version is live: the customer lifetime value calculator. Five inputs, one HTML file, no email required to see the result. This piece is how it was built, the prompt that built it, and what to do with it once it is on your site. I have made these for cleaning companies, salons and HVAC firms since 2018, so the numbers below come from that work rather than a template.
In numbers
- Five inputs a service business owner already knows, four outputs, result shown before any email
- Example: $180 a visit, six visits a year, three years, 45 percent margin gives one customer worth $3,240 and $1,458 in gross profit
- The exact build prompt is included and produces the finished file in one pass
- No conversion multiple quoted, because every one traces back to a quiz-software vendor
- Working file at farhanarshad.com/clv-calculator, free to copy
Why a calculator beats a PDF
A calculator gives the visitor something they cannot get from a document: their own number. A PDF tells everyone the same thing. A calculator tells each person what their situation is worth, and a figure you produced yourself lands harder than a figure someone told you. That is the whole psychology of the summit’s income calculator, and it works just as well for a plumber.
Three practical advantages follow. It segments your list, because the inputs tell you who is big and who is small before you ever speak to them. It gets shared, because a business owner who sees that one customer is worth $3,240 to them sends the link to their partner. And it never goes stale the way a “2026 guide” does.
One thing I refuse to put in this piece is a conversion multiple. Every “interactive content converts X times better” statistic I checked traces back to a company that sells quiz software and publishes no methodology. I would rather you test it on your own site than repeat a number I cannot stand behind.
What the calculator asks and shows
The calculator asks for five numbers a service business owner already knows. Average job value. Jobs per customer per year. Years a customer stays. Gross margin. New customers per month. From those it shows the lifetime revenue of one customer, the gross profit on that customer, the lifetime revenue a single year of new customers adds, and what six extra months of retention is worth per customer. It also states a rule of thumb: you can spend up to a third of gross profit per customer to win one and still keep two thirds.
Try it with a residential cleaning company: $180 a visit, six visits a year, three years, 45 percent margin, eight new customers a month. One customer is worth $3,240 in revenue and $1,458 in gross profit. A year of new customers adds $311,040 of lifetime revenue. Keeping each customer six months longer is worth $540 each. Those four numbers do more for a sales conversation than any brochure.
The exact prompt
The prompt below is the one I used, and it is written so that Claude produces the finished file in one pass rather than a chat about it. Paste it as is, then change the industry line and the default values.
Build a single-file HTML customer lifetime value calculator for a local service business. Five inputs: average job value, jobs per customer per year, years a customer stays, gross margin percent, new customers per month. Show four outputs that update as the user types, with no submit button: lifetime revenue per customer, gross profit per customer, lifetime revenue added by twelve months of new customers, and the extra lifetime revenue if each customer stays six months longer. Add one sentence of guidance under the result: the most you can spend to win a customer while keeping two thirds of the profit. Sensible defaults for a residential cleaning company. Plain JavaScript, no libraries, no external requests. Inputs use inputmode decimal for phones. The result block has aria-live polite. Mobile first, readable at 360 pixels wide. Do not ask for an email before showing the result.
The one instruction that matters most is the last one. Showing the result before asking for anything is what separates a tool from a bait page.
Want this done for your business?
An audit, a build, or a morning report on your own accounts. Tell me what you are trying to do and I reply myself within one working day.
How to put it on your site
Upload the file to your web host and link it from your homepage, your Google Business Profile and your email signature. It is one HTML file, so it works on WordPress, Shopify, Squarespace or a bare Hostinger folder. On WordPress, add it as a static file rather than a page template so nothing in the theme can break it.
Then add the two things that turn it into a lead magnet without gating it. Under the result, offer to email the numbers as a one-page summary, and make that optional. And add a line that says what you do for businesses that want the retention number to move. The people who fill in the form are the people who have just watched their own customer value appear on screen, which is the best moment you will ever get.
Track it in Google Analytics 4 with one custom event on the first input change and one on the form submit. That gives you a real conversion rate in a month, from your own traffic, instead of a number from a software vendor.
Common mistakes
What I see most often is calculators that ask for the email first. Nobody trusts a number they had to pay for with an inbox, and the drop-off before the result is brutal. Show the number, then ask.
The second mistake is too many inputs. Ten fields turns a tool into a form. Five is the limit for a business owner on a phone, and every one of them has to be a number they know without looking it up.
The third is a fake precision problem: showing $3,241.57 when the inputs were guesses. Round to whole currency, and say in the copy that the output is only as honest as the “years a customer stays” figure. An owner who puts in five years when the truth is eighteen months is lying to a calculator, and the calculator should say so gently.
Key takeaways
- A calculator gives each visitor their own number, which a PDF cannot do, and that number is what gets shared and remembered.
- Five inputs, four outputs, result shown before any email is requested.
- The working file is at farhanarshad.com/clv-calculator and is free to copy with your own branding.
- The build prompt above produces the finished file in one pass; change the industry and the defaults.
- Measure your own conversion rate with two GA4 events rather than quoting a vendor’s multiple.
The calculator file and the prompt are in the free toolkit. If you want one built for your business with your numbers and your branding, tell me about it.